A rough grinding liquid for a diamond substrate and a preparation method thereof, and a rough grinding method of a diamond substrate

Abstract

The application discloses a rough grinding liquid for diamond substrates and a preparation method thereof, and a rough grinding method for diamond substrates, and relates to the technical field of diamond processing. The rough grinding liquid for diamond substrates comprises the following components in mass parts: diamond 0.5-1.5 parts, dispersing agent 0.1-1 part, pH regulator 1-5 parts, suspending agent 0.1-1 part, and water 88-98 parts; wherein the D50 of the diamond is 10-50 mu m; the suspending agent comprises at least one of xanthan gum, carbomer, sodium polyacrylate and bentonite; and the dispersing agent comprises at least one of polymaleic anhydride, sodium pyrophosphate, anhydrous sodium metasilicate and polyacrylamide. The technical scheme of the application can solve the problems of low grinding rate, large surface roughness and high total thickness deviation of the existing grinding liquid for diamond substrates by adjusting the particle size of the abrasive and the composition of the suspending agent and the dispersing agent.

Description

Technical Field

[0001] This invention relates to the field of diamond processing technology, and in particular to a rough grinding fluid for diamond substrates, a method for preparing the same, and a method for rough grinding diamond substrates. Background Technology

[0002] Diamond, a material with extremely high hardness and brittleness, is widely used in various fields, such as electronics, optics, and tool manufacturing. Currently, diamond crystals require processes such as cutting, grinding, and polishing to be used industrially. Minor impurities and roughness on the diamond surface can affect its optical and electronic properties. Due to diamond's extremely high hardness, traditional polishing methods often cannot achieve atomic-level control over the diamond surface roughness, thus greatly limiting its applications.

[0003] Common diamond polishing processes generally consist of three steps: rough grinding, fine grinding, and fine polishing. Rough grinding aims to remove large defects, cracks, and uneven areas from the surface. Fine grinding (usually mechanical polishing) quickly removes the surface damage layer caused by the previous grinding process while maintaining flatness, reducing surface roughness. Fine polishing (usually chemical mechanical polishing) further improves the micro-roughness of the crystal surface through chemical corrosion and mechanical action, achieving a high surface finish. Currently, most rough grinding slurries used for diamond substrates employ single-crystal diamond for rough grinding, which results in problems such as low grinding rate, high surface roughness, and high TTV (Total Thickness Variation).

[0004] Therefore, there is an urgent need to develop a high-efficiency and low-cost coarse grinding fluid to solve the problems of low grinding rate, large surface roughness and high TTV of existing coarse grinding fluids for diamond substrates. Summary of the Invention

[0005] The main objective of this invention is to propose a coarse grinding fluid for diamond substrates and its preparation method, as well as a coarse grinding method for diamond substrates, in order to solve the problems of low grinding rate, large surface roughness, and high TTV in existing coarse grinding fluids for diamond substrates.

[0006] To achieve the above objectives, this invention provides a coarse grinding slurry for diamond substrates, comprising the following components in parts by weight: 0.5–1.5 parts diamond, 0.1–1 part dispersant, 1–5 parts pH adjuster, 0.1–1 part suspending agent, and 88–98 parts water; wherein:

[0007] The D50 of the diamond is 10μm to 50μm;

[0008] The suspending agent includes at least one of xanthan gum, carbomer, sodium polyacrylate, and bentonite;

[0009] The dispersant includes at least one of polymaleic anhydride, sodium pyrophosphate, anhydrous sodium metasilicate, and polyacrylamide.

[0010] In one embodiment, the pH adjuster includes at least one of sodium hydroxide, potassium hydroxide, triethanolamine, and ammonia.

[0011] In one embodiment, the pH value of the coarse grinding fluid for the diamond substrate is 7 to 9.

[0012] In one embodiment, the viscosity of the coarse grinding fluid for the diamond substrate is 1500–3000 mPa·s.

[0013] This invention proposes a method for preparing the coarse grinding fluid for diamond substrates, comprising the following steps:

[0014] A1. Mix diamond and water to obtain a diamond solution;

[0015] A2. Mix the diamond solution, dispersant, and suspending agent to obtain a mixed solution;

[0016] A3. Add a pH adjuster to the mixed solution to obtain the coarse grinding fluid for diamond substrates.

[0017] In one embodiment, step A1 includes:

[0018] Diamond and water are mixed in a stirred tank to obtain a diamond solution; wherein:

[0019] The frequency of the stirred tank is 15–20 Hz; and / or,

[0020] The stirring time in the stirred tank is 20 to 40 minutes.

[0021] In one embodiment, step A1 includes:

[0022] First, add water to the stirred tank, start the stirred tank, then add diamond, mix, and obtain a diamond solution.

[0023] In one embodiment, step A2 includes:

[0024] A diamond solution, a dispersant, and a suspending agent are mixed in a stirred tank to obtain a mixed solution; wherein:

[0025] The frequency of the stirred tank is 25–35 Hz; and / or,

[0026] The stirring time in the stirred tank is 20 to 40 minutes.

[0027] This invention proposes a method for rough grinding of diamond substrates, comprising the following steps:

[0028] B1. Provide a diamond substrate;

[0029] B2. Apply coarse grinding fluid to the diamond substrate and perform coarse grinding to obtain a coarsely ground diamond substrate.

[0030] The coarse grinding fluid is either the coarse grinding fluid for diamond substrates described in the above technical solution or the coarse grinding fluid for diamond substrates prepared by the preparation method described in the above technical solution.

[0031] In one embodiment, in step B2, the grinding rate of the coarse grinding is 10-12 μm / h.

[0032] The beneficial effects of the technical solution of the present invention are as follows:

[0033] The coarse grinding fluid provided by this invention uses micron-sized diamonds with a particle size of 10μm to 50μm as the abrasive, reducing the possibility of scratches during coarse grinding. Furthermore, micron-sized diamonds possess excellent hardness and wear resistance, as well as uniform particle size distribution, which helps achieve consistent processing results during coarse grinding, reducing surface roughness and TTV, and improving processing accuracy. Micron-sized diamonds also have high purity and low impurity content, reducing the possibility of introducing additional contaminants during coarse grinding and helping to improve the quality of the processed surface. The selection of specific suspending and dispersing agents ensures that the abrasive is uniformly distributed in the liquid phase, which is beneficial for improving the quality of the processed surface. Therefore, the technical solution of this invention, by adjusting the abrasive particle size and the composition of the suspending and dispersing agents, obtains a coarse grinding fluid with good dispersibility and suspension. This allows the abrasive in the grinding fluid to remain in a uniform, non-precipitated state for a long period. Using the coarse grinding fluid provided by this invention can effectively avoid scratches on the workpiece surface, increase the grinding rate during the coarse grinding process, and result in a superior processed diamond substrate with a smaller total thickness deviation. This can improve upon the problems of low grinding rate, high surface roughness, and high total thickness deviation found in existing coarse grinding fluids for diamond substrates. Furthermore, the coarse grinding fluid provided by this invention does not require complex modification of the abrasive, the addition of special additives, or special grinding processes, offering advantages of low cost and high efficiency, which is beneficial for large-scale application. Detailed Implementation

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0036] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0037] Diamond, a material with extremely high hardness and brittleness, is widely used in various fields, such as electronics, optics, and tool manufacturing. Currently, diamond crystals require processes such as cutting, grinding, and polishing to be used industrially. Minor impurities and roughness on the diamond surface can affect its optical and electronic properties. Due to diamond's extremely high hardness, traditional polishing methods often cannot achieve atomic-level control over the diamond surface roughness, thus greatly limiting its applications.

[0038] Common diamond polishing processes generally consist of three steps: rough grinding, fine grinding, and fine polishing. Rough grinding aims to remove large defects, cracks, and uneven parts from the surface. Fine grinding (usually mechanical polishing) quickly removes the surface damage layer caused by the previous grinding process while ensuring flatness, thus reducing surface roughness. Fine polishing (usually chemical mechanical polishing) further improves the micro-roughness of the crystal surface through chemical corrosion and mechanical action, achieving a high-gloss finish.

[0039] Currently, most coarse grinding slurries used for diamond substrates employ large-particle-size single-crystal diamonds (50–100 μm) for coarse grinding. This results in slow grinding speeds, and after coarse grinding, the surface roughness of the diamond substrate is typically 300–500 nm, with a total thickness variation (TTV) of 20–30 μm. Therefore, there is an urgent need to develop a high-efficiency and low-cost coarse grinding slurry to address the problems of low grinding rate, high surface roughness, and high total thickness variation found in existing coarse grinding slurries for diamond substrates.

[0040] In view of this, the present invention provides a rough grinding slurry for diamond substrates, wherein the rough grinding slurry for diamond substrates comprises the following components in parts by weight: 0.5-1.5 parts diamond, 0.1-1 parts dispersant, 1-5 parts pH adjuster, 0.1-1 parts suspending agent, and 88-98 parts water; wherein:

[0041] The D50 of the diamond is 10μm to 50μm;

[0042] The suspending agent includes at least one of xanthan gum, carbomer, sodium polyacrylate, and bentonite;

[0043] The dispersant includes at least one of polymaleic anhydride, sodium pyrophosphate, anhydrous sodium metasilicate, and polyacrylamide.

[0044] The coarse grinding fluid provided by this invention uses micron-sized diamonds with a particle size of 10μm to 50μm as the abrasive, reducing the possibility of scratches during coarse grinding. Furthermore, micron-sized diamonds possess excellent hardness and wear resistance, as well as uniform particle size distribution, which helps achieve consistent processing results during coarse grinding, reducing surface roughness and TTV, and improving processing accuracy. Micron-sized diamonds also have high purity and low impurity content, reducing the possibility of introducing additional contaminants during coarse grinding and helping to improve the quality of the processed surface. The selection of specific suspending and dispersing agents ensures that the abrasive is uniformly distributed in the liquid phase, which is beneficial for improving the quality of the processed surface. Therefore, the technical solution of this invention, by adjusting the abrasive particle size and the composition of the suspending and dispersing agents, obtains a coarse grinding fluid with good dispersibility and suspension. This allows the abrasive in the grinding fluid to remain in a uniform, non-precipitated state for a long period. Using the coarse grinding fluid provided by this invention can effectively avoid scratches on the workpiece surface, increase the grinding rate during the coarse grinding process, and result in a superior processed diamond substrate with a smaller total thickness deviation. Therefore, it can be used to improve the problems of low grinding rate, large surface roughness, and high total thickness deviation in existing diamond substrate grinding fluids. Furthermore, the coarse grinding fluid provided by this invention does not require complex modification of the abrasive, the addition of special additives, or special grinding processes, offering advantages of low cost and high efficiency, which is beneficial for large-scale application.

[0045] It should be noted that dispersants are used to uniformly disperse abrasive particles in a liquid medium. Without dispersants, abrasive particles in the grinding fluid are prone to agglomeration, leading to poor grinding results and high surface roughness. Suspensions are used to improve the suspension stability of abrasive particles in the grinding fluid, prevent sedimentation, and also have a certain lubricating effect, which is beneficial to improving the quality of the processed surface. Conventional suspending agents used for diamond substrates are cellulose, which has a high viscosity and can affect processing; conventional dispersants used for diamond substrates are organic dispersants. Compared with conventional suspending agents, the suspending agent in this invention can maintain a better suspension effect under lower viscosity conditions, has less impact on processing, and is beneficial to improving the quality of the processed surface; compared with conventional dispersants, the dispersing agent in this invention is an inorganic dispersant, with a more stable composition and a better dispersion effect on diamond.

[0046] In embodiments of the present invention, the pH adjuster includes at least one of sodium hydroxide, potassium hydroxide, triethanolamine, and ammonia.

[0047] In an embodiment of the present invention, the pH value of the coarse grinding slurry for the diamond substrate is 7 to 9. Setting the pH value of the coarse grinding slurry within the above range is beneficial for the suspending agent to maintain a good suspension effect.

[0048] In embodiments of the present invention, the viscosity of the coarse grinding slurry for diamond substrates is 1500–3000 mPa·s. If the viscosity is too low, the slurry is easily thrown off the grinding disc during grinding, affecting the grinding rate; if the viscosity is too high, the slurry has relatively poor fluidity, low chip removal capacity, and the grinding chips easily clog the grinding disc, causing high disc temperature and excessive TTV. Setting the viscosity of the coarse grinding slurry to 1500–3000 mPa·s is beneficial for controlling the surface profile and grinding rate of the workpiece.

[0049] This invention proposes a method for preparing the coarse grinding fluid for diamond substrates, comprising the following steps:

[0050] A1. Mix diamond and water to obtain a diamond solution;

[0051] A2. Mix the diamond solution, dispersant, and suspending agent to obtain a mixed solution;

[0052] A3. Add a pH adjuster to the mixed solution to obtain the coarse grinding fluid for diamond substrates.

[0053] The preparation method described in this invention specifies the order in which the components are added. Specifically, diamond is first slowly added to water to avoid agglomeration due to rapid addition. Then, a dispersant and a suspending agent are added to maintain a stable suspension in the mixed solution. Finally, a pH adjuster is added to activate the suspending agent, thus obtaining the coarse polishing slurry for diamond substrates. The coarse polishing slurry prepared using the method provided in this invention exhibits good stability and polishing effect.

[0054] In an embodiment of the invention, the diamond is subjected to large-particle sieving before step A1, so that the diamond particle size is in the range of 10μm to 50μm. During the grinding process, large particles, due to their larger size and higher indentation depth, are prone to producing deep scratches on the diamond substrate surface, causing damage. Therefore, large-particle sieving of the abrasive before coarse grinding can reduce scratches and improve the grinding effect and product quality.

[0055] In an embodiment of the present invention, step A1 includes:

[0056] Diamond and water are mixed in a stirred tank to obtain a diamond solution; wherein:

[0057] The frequency of the stirring vessel is 15-20Hz;

[0058] The stirring time in the stirred tank is 20 to 40 minutes.

[0059] The technical solution of the present invention selects to add abrasive at a lower frequency, and sets the frequency and stirring time of the stirring vessel within the above range, so that the diamond powder is more fully dispersed.

[0060] In an embodiment of the present invention, step A1 includes:

[0061] First, add water to the stirred tank, start the stirred tank, then add diamond, mix, and obtain a diamond solution.

[0062] The technical solution of this invention involves adding water first, and then slowly adding diamonds to the water to avoid the agglomeration of micron-sized diamonds caused by rapid addition. The diamonds can be added in multiple batches.

[0063] In an embodiment of the present invention, step A2 includes:

[0064] A diamond solution, a dispersant, and a suspending agent are mixed in a stirred tank to obtain a mixed solution; wherein:

[0065] The frequency of the stirring vessel is 25-35Hz;

[0066] The stirring time in the stirred tank is 20 to 40 minutes.

[0067] The technical solution of this invention selects a relatively high frequency for mixing the diamond solution, dispersant, and suspending agent. Setting the frequency and stirring time of the stirred tank within the aforementioned range ensures that the suspending agent is fully dissolved and effective. Below this range, the mixed solution will not be sufficiently stirred, affecting the suspension effect; above this range, the viscosity of the suspending agent will change.

[0068] This invention proposes a method for rough grinding of diamond substrates, comprising the following steps:

[0069] B1. Provide a diamond substrate;

[0070] B2. Apply coarse grinding fluid to the diamond substrate and perform coarse grinding to obtain a coarsely ground diamond substrate.

[0071] The coarse grinding fluid is either the coarse grinding fluid for diamond substrates described in the above technical solution or the coarse grinding fluid for diamond substrates prepared by the preparation method described in the above technical solution.

[0072] The coarse grinding fluid provided by this invention does not require a special grinding process; conventional grinding processes can be followed. In an embodiment of this invention, the grinding is performed in a 9B double-sided grinding machine, and the grinding process parameters are: polishing pressure of 100–200 g / cm². 2 The rotation speed is 20-50 rpm, the flow rate is 100-300 mL / min, and the grinding disc temperature is 20-30℃.

[0073] In an embodiment of the present invention, in step B2, the grinding rate of the coarse grinding is 10–12 μm / h. The technical solution of the present invention, by selecting diamond with a particle size of 10 μm–50 μm as the abrasive, and by selecting specific suspending and dispersing agents, can effectively improve the polishing rate of diamond substrates while ensuring high-quality polishing results.

[0074] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0075] In the following embodiments, the diamond has a D50 of 20 μm.

[0076] Example 1

[0077] A coarse grinding slurry for diamond substrates comprises 1 part diamond, 0.4 parts anhydrous sodium metasilicate, 0.3 parts xanthan gum, 3 parts sodium hydroxide and 96.5 parts water.

[0078] Example 2

[0079] A coarse grinding slurry for diamond substrates comprises 0.7 parts diamond, 0.2 parts sodium pyrophosphate, 0.5 parts carbomer, 4 parts pH potassium hydroxide, and 94.6 parts water.

[0080] Example 3

[0081] A coarse grinding slurry for diamond substrates comprises 1.2 parts diamond, 0.5 parts sodium pyrophosphate, 0.5 parts carbomer, 5 parts potassium hydroxide and 92.8 parts water.

[0082] Example 4

[0083] A method for preparing a roughing slurry for diamond substrates includes the following steps:

[0084] (1) Add 96.5 parts of water to the stirred tank, set the frequency of the stirred tank to 20Hz, start the stirred tank, add 1 part of micron diamond, stir for 30 minutes to obtain diamond solution;

[0085] (2) Add 0.4 parts of anhydrous sodium metasilicate and 0.3 parts of xanthan gum to the diamond solution in step (1), increase the frequency of the stirring vessel to 30 Hz, and stir for 30 min to obtain a mixed solution;

[0086] (3) Add sodium hydroxide to the mixed solution in step (2) to adjust the pH value of the system to the range of 7 to 9, and obtain the coarse grinding solution for diamond substrate.

[0087] Comparative Example 1

[0088] The difference from Example 1 is that xanthan gum is replaced with sodium carboxymethyl cellulose.

[0089] Comparative Example 2

[0090] The difference from Example 1 is that anhydrous sodium metasilicate is replaced with BYK-154.

[0091] Comparative Example 3

[0092] Compared with Example 1, the difference is that xanthan gum is replaced with sodium carboxymethyl cellulose and anhydrous sodium metasilicate is replaced with BYK-154.

[0093] Comparative Example 4

[0094] The difference compared to Example 1 is that the diamond particle size is 5 μm.

[0095] Comparative Example 5

[0096] The difference compared to Example 1 is that the diamond particle size is 100 μm.

[0097] Performance testing

[0098] The viscosity of the coarse grinding fluids in Examples 1-4 and Comparative Examples 1-5 was tested using a viscometer, and the test results are shown in Table 1.

[0099] The diamond substrates were coarsely ground using the coarse grinding slurries of Examples 1-4 and Comparative Examples 1-5. After coarse grinding, the diamond substrates were washed and dried. Then, the grinding rate, surface roughness, and total thickness deviation were measured. The process parameters and test methods for coarse grinding are as follows:

[0100] Rough grinding: Grinding is carried out in a 9B double-sided grinding machine with the following process parameters: polishing pressure 150g / cm. 2 The rotation speed was 40 rpm, the flow rate was 200 mL / min, and the grinding disc temperature was 25℃.

[0101] The grinding rate was tested using an analytical balance. The grinding rate was calculated as follows: Grinding rate = Δm * 10000 / (ρ * s * t), where Δm (g) is the change in the weight of the workpiece during rough grinding, ρ is the density of the diamond substrate (ρ = 3.52 g / cm2), s is the surface area of ​​the workpiece, and t is the polishing time. The test results are shown in Table 1.

[0102] Surface roughness test method: The surface roughness was tested using a white light interferometer, and the test results are shown in Table 1.

[0103] Total Thickness Deviation (TTV) Test Method: The thickness of the diamond substrate is measured using a micrometer. The difference in thickness between the thickest and thinnest points is the TTV. The test results are shown in Table 1.

[0104] Table 1 Performance tests of the coarse grinding fluids in Examples 1-4 and Comparative Examples 1-5

[0105]

[0106]

[0107] As shown in Table 1, the grinding rate, surface roughness and total thickness deviation test results of the coarse grinding fluid of Example 1 are better than those of Comparative Examples 1-3. Furthermore, the coarse grinding fluids of Examples 1-4 have better overall performance, indicating that the coarse grinding fluid provided by the present invention can balance grinding rate and processing effect, effectively improve grinding rate and reduce surface roughness and TTV of diamond substrate.

[0108] Table 1 also shows that although the coarse grinding fluid of Comparative Example 4 can also achieve a lower surface roughness and TTV, the grinding rate is lower. Although the grinding rate is faster when using the coarse grinding fluid of Comparative Example 5, the test results of surface roughness and TTV are worse.

[0109] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A coarse grinding fluid for diamond substrates, characterized in that, The composition comprises the following components in parts by weight: 0.5-1.5 parts diamond, 0.1-1 parts dispersant, 1-5 parts pH adjuster, 0.1-1 parts suspending agent, and 88-98 parts water; wherein: The D50 of the diamond is 10 μm to 50 μm; The suspending agent includes at least one of xanthan gum, carbomer, sodium polyacrylate, and bentonite; The dispersant includes at least one of sodium pyrophosphate and anhydrous sodium metasilicate; The viscosity of the coarse grinding fluid used for diamond substrates is 1500~3000 mPa·s.

2. The coarse grinding fluid for diamond substrates as described in claim 1, characterized in that, The pH adjuster includes at least one of sodium hydroxide, potassium hydroxide, triethanolamine, and ammonia.

3. The coarse grinding fluid for diamond substrates as described in claim 1, characterized in that, The pH value of the coarse grinding fluid used for diamond substrates is 7-9.

4. A method for preparing a roughing slurry for diamond substrates as described in any one of claims 1 to 3, characterized in that, Includes the following steps: A1. Mix diamond and water to obtain a diamond solution; A2. Mix the diamond solution, dispersant, and suspending agent to obtain a mixed solution; A3. Add a pH adjuster to the mixed solution to obtain the coarse grinding fluid for diamond substrates.

5. The method for preparing the roughing slurry for diamond substrates as described in claim 4, characterized in that, Step A1 includes: Diamond and water are mixed in a stirred tank to obtain a diamond solution; wherein: The frequency of the stirred tank is 15~20 Hz; and / or, The stirring time in the stirred tank is 20-40 minutes.

6. The method for preparing the roughing slurry for diamond substrates as described in claim 5, characterized in that, Step A1 includes: First, add water to the stirred tank, start the stirred tank, then add diamond, mix, and obtain a diamond solution.

7. The method for preparing the roughing slurry for diamond substrates as described in claim 4, characterized in that, Step A2 includes: A diamond solution, a dispersant, and a suspending agent are mixed in a stirred tank to obtain a mixed solution; wherein: The frequency of the stirred tank is 25~35 Hz; and / or, The stirring time in the stirred tank is 20-40 minutes.

8. A method for rough grinding a diamond substrate, characterized in that, Includes the following steps: B1. Provide a diamond substrate; B2. Apply coarse grinding fluid to the diamond substrate and perform coarse grinding to obtain a coarsely ground diamond substrate. The coarse grinding fluid is the coarse grinding fluid for diamond substrates as described in any one of claims 1 to 3, or the coarse grinding fluid for diamond substrates prepared by the preparation method of the coarse grinding fluid for diamond substrates as described in any one of claims 4 to 7.

9. The rough grinding method for a diamond substrate as described in claim 8, characterized in that, In step B2, the grinding rate of the coarse grinding is 10~12 μm / h.

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